Spinel Nanostructures for the Hydrogenation of CO2 to Methanol and Hydrocarbon Chemicals.

Composite oxides have been widely applied in the hydrogenation of CO/CO2 to methanol or as the component of bifunctional oxide-zeolite for the synthesis of hydrocarbon chemicals. However, it is still challenging to disentangle the stepwise formation mechanism of CH3OH at working conditions and selectively convert CO2 to hydrocarbon chemicals with narrow distribution. Here, we investigate the reaction network of the hydrogenation of CO2 to methanol over a series of spinel oxides (AB2O4), among which the Zn-based nanostructures offer superior performance in methanol synthesis. Through a series of (quasi) in situ spectroscopic characterizations, we evidence that the dissociation of H2 tends to follow a heterolytic pathway and that hydrogenation ability can be regulated by the combination of Zn with Ga or Al. The coordinatively unsaturated metal sites over ZnAl2Ox and ZnGa2Ox originating from oxygen vacancies (OVs) are evidenced to be responsible for the dissociative adsorption and activation of CO2. The evolution of the reaction intermediates, including both carbonaceous and hydrogen species at high temperatures and pressures over the spinel oxides, has been experimentally elaborated at the atomic level. With the integration of a series of zeolites or zeotypes, high selectivities of hydrocarbon chemicals with narrow distributions can be directly produced from CO2 and H2, offering a promising route for CO2 utilization.

[Distribution and Environmental Significance of Rare Earth Elements in Typical Protected Vegetable Soil, Northern China].

The concentrations of rare earth elements (REEs) in protected vegetable soils in Wuqing district of Tianjin City, Jinzhong district of Shanxi Province, Shenyang district of Liaoning Province, and Wulanchabu district of Inner Mongolia Autonomous Region in northern China were measured to analyze the change characteristics of soil REEs in the process of protected vegetable cultivation. Additionally, we sought to use the REEs parameters to trace the feasibility of characterizing the interference of human activities on the soil ecological environment. The results showed that the total content of REEs (REE) in the topsoil of protected vegetable fields ranged from 146.52 to 158.76 mg·kg-1, with an average of 152.34 mg·kg-1 in Shenyang; 92.16 to 137.69 mg·kg-1, with an average of 115.03 mg·kg-1in Wuqing; 91.38 to 118.84 mg·kg-1, with an average of 108.03 mg·kg-1 in Wulanchabu; and 97.62 to 111.27 mg·kg-1, with an average of 102.43 mg·kg-1in Jinzhong. The REEs distribution patterns in the soils of the four areas, standardized with chondrite, characterized by a right tilt, showed that light rare earth elements were obviously enriched in the soil, demonstrated by the ratios of LREE/HREE and (La/Yb) N, which were greater than 6 and 7, respectively. The values of (La/Sm)N in the soils were higher than 3, suggesting that there was an obvious fractionation between light rare earth elements, whereas the values of (Gd/Yb)N were between 1-2, and there was a weak fractionation between heavy rare earth elements. The values of δEu in the soils were between 0.56 and 0.61, showing that Eu had a negative abnormality. The values of δCe were between 0.89 and 1.11, showing that Ce had no abnormality or weak positive abnormality. The higher LREE/HREE and (La/Yb)N in protected vegetable soil than that in open-air vegetable soil indicated the increasing differentiation degree between light and heavy rare earth elements in protected vegetable soil. The lower (La/Sm)N in protected vegetable soils indicated the reduction in the differentiation among light rare earth elements in soil. Higher δCe values and lower δEu values suggested that Ce and Eu were relatively enriched and depleted, respectively, during vegetable planting. The REE, LREE, (La/Sm)N, and δEu in protective soil decreased with the number of cultivation years, whereas the (Gd/Yb)N and δCe increased, but the HREE values did not change significantly. There was a significant correlation between δCe, δEu, (La/Yb)N, (Gd/Yb)N, and soil bulk density, soil moisture content, and soil organic matter in Tianjin protected vegetable soils, showing preliminarily that rare earth elements can be used as tracer elements to characterize the interference intensity of human activities on soil.

Mapping the structure of depression biomarker research: A bibliometric analysis.

Background: Depression is a common mental disorder and the diagnosis is still based on the descriptions of symptoms. Biomarkers can reveal disease characteristics for diagnosis, prognosis, and treatment. In recent years, many biomarkers relevant to the mechanisms of depression have been identified. This study uses bibliometric methods and visualization tools to analyse the literature on depression biomarkers and its hot topics, and research frontiers to provide references for future research. Methods: Scientific publications related to depression biomarkers published between 2009 and 2022 were obtained from the Web of Science database. The BICOMB software was used to extract high-frequency keywords and to construct binary word-document and co-word matrices. gCLUTO was used for bicluster and visual analyses of high-frequency keywords. Further graphical visualizations were generated using R, CiteSpace and VOSviewer software. Results: A total of 14,403 articles related to depression biomarkers were identified. The United States (34.81%) and China (15.68%), which together account for more than half of all publications, can be considered the research base for the field. Among institutions, the University of California, University of London, and Harvard University are among the top in terms of publication number. Three authors (Maes M, Penninx B.W.J.H., and Berk M) emerged as eminent researchers in the field. Finally, eight research hotspots for depression biomarkers were identified using reference co-citation analysis. Conclusion: This study used bibliometric methods to characterize the body of literature and subject knowledge in the field of depression biomarker research. Among the core biomarkers of depression, functional magnetic resonance imaging (fMRI), cytokines, and oxidative stress are relatively well established; however, research on machine learning, metabolomics, and microRNAs holds potential for future development. We found "microRNAs" and "gut microbiota" to be the most recent burst terms in the study of depression biomarkers and the likely frontiers of future research.